1. Field of the Invention
This invention relates to a device for the controlling of a variable-moment vibrator such as e.g. the one described in U.S. Pat. No. 5,253,542, filed on Jul. 14, 1992 in the name of the filing party hereof and patented on Oct. 19, 1993.
2. Description of the Prior Art
It is a known fact that vibrators of this type serving e.g. to drive objects such as stakes or sheet piles into the ground, use at least one pair of off-center rotating feeders, or even two trains of feeders driven in opposite direction to one another, at a same rotational speed.
With a view to regulating the amplitude of the vibrations generated by the vibrator, especially to avoid harmful transitional phenomena during the start-up and shutdown phases, and to take the mechanical characteristics of the ground into account, devices have been proposed enabling an angular displacement to be generated between the two feeders of the pair or between the two trains of feeders.
Such devices can use a Pecqueur-type planetary gear train, as described in French patent No. 1,566,358 in the name of the filing party hereof, or even a rotating link using a hydraulically controlled phase shifter, e.g. of the type comprising two rotating elements axially mobile in relation to one another and against the action of a spring, under the effect of a pressurized fluid.